Fig. 5.

A: diastolic Ca²⁺ levels were lower in sedentary transgenic (TG) CaMKIIδ_C-overexpressing mice_, but this was raised to sedentary WT levels by exercise training; exercise training had, however, no effect in WT. B: time to 50% Ca²⁺ decay was prolonged in TG mice compared with WT but reduced by exercise training to WT levels; exercise training also reduced time to 50% Ca²⁺ decay in WT. C: example traces of Ca²⁺ transients evoked by twitch stimulations and caffeine stimulations. D: calculated NCX rate constant of Ca²⁺ removal; the NCX rate was increased in TG, whereas exercise training normalized the rate. Exercise training had no effect in WT. E: calculated SERCA2a rate constant of Ca²⁺ removal; SERCA2a rate was reduced in TG mice compared with WT, whereas exercise training increased the rate in both TG and WT. **P < 0.01 vs. other groups, *P < 0.05 vs. WT. Cells in each group n = 25–30. F: protein expression of SERCA2a (protein expressions are presented as means ± SE, number of mice in each group N = 4, no significant differences were observed between groups).